The Terahertz Imaging Detection machine (pictured) reads terahertz, radioactive energy that people and inanimate objects naturally emit. This would allow police officers to view hidden weapons from a distance without having to conduct a physical search.

“If something is obstructing the flow of that radiation, for example a weapon, the device will highlight that object,” Kelly said during the police foundation breakfast, according to the New York Daily News.

Constant cries and protests have been heard and targeted towards Stop And Frisk, the long derided police policy of stopping and searching civilians suspected of harboring weapons or other contraband. Minority communities have been disproportionately affected by the practice, as the majority of those stopped and searched happen to be disproportionally black and Latino–and innocent.

Now the question is whether this device can really be a justifiable stand-in for Stop And Frisk?

The New York Civil Liberties Union doesn’t think so. The organization previously sued the city over Stop And Frisk, noting its concern over “virtual pat downs” when the technology was first introduced last year.

Watch a news report about the technology:

“It’s worrisome. It implicates privacy, the right to walk down the street without being subjected to a virtual pat-down by the Police Department when you’re doing nothing wrong,” said Donna Lieberman, the NYCLU Director.

A video image of the technology in use was shown at the breakfast Wednesday. It showed an officer dressed in plainclothes with a clear gun shape hidden under his jersey when seen through the machine. Street testing of the device is set to begin shortly. It is small enough to be placed in a police vehicle or at street corners known for gun violence.

Kelly has previously stated that the scanner would only be used in extreme circumstances.

“You could use it at a specific event. You could use it at a shooting-prone location,” he told CBS 2 last year.